A coated steel material including: a base steel, and a coating layer containing a Zn-Al-Mg alloy layer disposed on a surface of the base steel, wherein the coating layer has a predetermined chemical composition, and, in a backscattered electron image of the Zn-Al-Mg alloy layer that is obtained at a time of observing the surface of the Zn-Al-Mg alloy layer after polishing to 1/2 of the layer thickness, under a scanning electron microscope at a magnification of 100X, Al crystals are present, and the average value of the cumulative circumferential length of the Al crystals is 88 to 195 mm/mm 2 .